So, I'm trying to work out how to accurately calculate the RTD temperature of a given resistance with a decent number of decimal places.
I have done the maths and calculated the temperature coefficient and so on but don't get a result that matches up with what I expect to satisfy a set specification. The maths doesn't match up with the internet calculators and makes it so my readings look to be way out. Either my calculations are wrong or the item I am calibrating is out of spec. I can't imagine it would be as it is a Beamex calibrator and they're usually pretty spot on. I expected the maths to be more accurate but I am having doubts in how to apply it to a real world application.
The calculations I did were using the formulas
And
Where equation 1 is calculating the coefficient using the RTD resistance at 0 degs and 100 degs and 2 the resistance temperature.
The result of these calculations do not match up with the internet calcs which is basically what I'm saying.
There are both different types with different temperature coefficients, and the TC is not absolutely linear, with most types - the simple equations give reasonable approximations only.
This seems to be a good page for overall info on them: